U.S. patent application number 15/150637 was filed with the patent office on 2016-11-17 for systems and methods for reducing pressure at an outflow of a duct.
This patent application is currently assigned to White Swell Medical Ltd. The applicant listed for this patent is White Swell Medical Ltd. Invention is credited to Tanhum Feld, Yaacov Nitzan, Menashe Yacoby.
Application Number | 20160331378 15/150637 |
Document ID | / |
Family ID | 57248934 |
Filed Date | 2016-11-17 |
United States Patent
Application |
20160331378 |
Kind Code |
A1 |
Nitzan; Yaacov ; et
al. |
November 17, 2016 |
SYSTEMS AND METHODS FOR REDUCING PRESSURE AT AN OUTFLOW OF A
DUCT
Abstract
Various systems and methods are provided for reducing pressure
at an outflow of a duct such as the thoracic duct or the lymphatic
duct. In one embodiment, an indwelling catheter can be configured
to be at least partially implanted within a vein of a patient in
the vicinity of an outflow port of a duct of the lymphatic system.
The catheter can include first and second restrictors each
configured to at least partially occlude the vein within which the
catheter is implanted and thus to restrict fluid flow within the
vein when the restrictors are activated. The restrictors can each
be configured to move between an activated configuration, in which
the restrictor occludes the vein, and a relaxed configuration, in
which the restrictor does not occlude the vein. The catheter can
include a pump, such as an axial motor pump, configured to pump
fluid through the catheter.
Inventors: |
Nitzan; Yaacov; (Hertzelia,
IL) ; Yacoby; Menashe; (Ramat Gan, IL) ; Feld;
Tanhum; (Merhavya, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
White Swell Medical Ltd |
Rishpon |
|
IL |
|
|
Assignee: |
White Swell Medical Ltd
Rishpon
IL
|
Family ID: |
57248934 |
Appl. No.: |
15/150637 |
Filed: |
May 10, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62159465 |
May 11, 2015 |
|
|
|
62233802 |
Sep 28, 2015 |
|
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61M 1/1018 20140204;
A61M 1/101 20130101; A61B 17/12109 20130101; A61B 17/12045
20130101; A61M 1/1086 20130101; A61M 1/125 20140204; A61M 2205/3303
20130101; A61M 1/1008 20140204; A61M 1/1029 20140204; A61M 1/1034
20140204; A61M 2202/0405 20130101; A61B 17/12036 20130101; A61M
2205/33 20130101; A61M 2205/32 20130101; A61M 1/122 20140204; A61B
17/12136 20130101 |
International
Class: |
A61B 17/12 20060101
A61B017/12; A61M 25/10 20060101 A61M025/10; A61M 1/00 20060101
A61M001/00; A61M 25/00 20060101 A61M025/00 |
Claims
1. An indwelling catheter configured to be implantable within a
vein of a patient, comprising: a sheath configured to be at least
partially implantable within a patient's vein, the sheath having a
lumen extending therethrough; a catheter shaft movably positioned
within and extending through the lumen of the sheath, the catheter
shaft being configured to be at least partially implantable within
a patient's vein and a proximal end extending from a proximal end
of the sheath and a distal end extending from a distal end of the
sheath, the catheter shaft having a suction lumen extending
therethrough, and one or more suction ports disposed therein and in
fluid communication with the suction lumen; a flexible membrane
attached to a distal portion of the catheter shaft, the flexible
membrane being a collapsible, tube-like member having a lumen
extending therethrough; a selectively deployable restriction member
formed over a portion of the flexible membrane; and at least one
inflation lumen extending through the catheter shaft, the at least
one inflation lumen being in fluid communication with the
restriction member.
2. The indwelling catheter of claim 1, wherein the indwelling
catheter includes a cone shaped tip at the distal end of the
catheter shaft.
3. The indwelling catheter of claim 1, wherein the flexible
membrane is coupled to an outer wall of the catheter shaft along a
length of the flexible membrane.
4. (canceled)
5. The indwelling catheter of claim 1, wherein the flexible
membrane is oriented so as to be substantially parallel to the
catheter shaft.
6. The indwelling catheter of claim 1, wherein the restriction
member is a selectively expandable balloon coupled to an outer wall
of the flexible membrane.
7. The indwelling catheter of claim 1, further comprising a second
selectively deployable restriction member formed over a distal
portion of the flexible membrane; and wherein the restriction
member is formed over a proximal portion of the flexible membrane
and the at least one inflation lumen is in fluid communication with
the second restriction member.
8. The indwelling catheter of claim 7, wherein the second
selectively deployable restriction member is a selectively
expandable balloon coupled to an outer wall of the flexible
membrane.
9. The indwelling catheter of claim 7, wherein a first pressure
port is disposed proximally of the first restriction member and a
second pressure port is disposed between the first and second
selectively deployable restriction members.
10. The indwelling catheter of claim 1, wherein a first inflation
port is disposed in an outer wall of the of the flexible membrane
and in fluid communication with the first selectively deployable
restriction member and a second inflation port is disposed on the
outer wall of the flexible member and in fluid communication with
the second selectively deployable restriction member.
11-19. (canceled)
20. A medical system, comprising: a catheter shaft configured to be
positioned within a vein of a patient; a first selectively
deployable restrictor coupled to the catheter shaft and configured
to be positioned within the vein; a second selectively deployable
restrictor coupled to the catheter shaft at a location distal to
the first restrictor such that a distance spans between the first
and second restrictors, the second restrictor being configured to
be positioned within the vein; at least one inlet opening formed
through a sidewall of the catheter shaft at a location between the
first and second restrictors; and a pump configured to facilitate
suction of fluid into the catheter shaft through the at least one
inlet opening.
21. The system of claim 20, wherein the first and second
restrictors each include a balloon.
22. The system of claim 21, further comprising at least one
inflation lumen extending along the catheter shaft, the at least
one inflation lumen being in fluid communication with the first and
second restrictors.
23-24. (canceled)
25. The system of claim 20, wherein the first restrictor is movable
between an activated configuration in which the first restrictor
has a first diameter and a relaxed configuration in which the first
restrictor has a second diameter that is less than the first
diameter, and the second restrictor is movable between an activated
configuration in which the second restrictor has a third diameter
and a relaxed configuration in which the second restrictor has a
fourth diameter that is less than the third diameter.
26-27. (canceled)
28. The system of claim 20, wherein the first and second
restrictors each include a stent.
29. The system of claim 20, further comprising at least one
additional inlet opening formed through the sidewall of the
catheter shaft at a location that is proximal to the first and
second restrictors.
30-34. (canceled)
35. The system of claim 20, further comprising a controller
configured to actuate the pump, wherein the controller is
configured to actuate the pump in response to user operation of a
control external to the body of the patient.
36. The system of claim 20, further comprising a controller
configured to actuate the pump; and a pressure sensor configured to
be implanted in the body of the patient, the controller being
configured to actuate the pump in response to a pressure measured
by the pressure sensor exceeding a predefined threshold.
37. The system of claim 20, further comprising a controller
configured to actuate the pump; and a pressure sensor configured to
be implanted in the body of the patient, the controller being
configured to control a speed of operation of the pump depending on
a pressure measured by the pressure sensor.
38. (canceled)
39. The system of claim 20, further comprising a flexible membrane
attached to a distal portion of the catheter shaft, the flexible
membrane being a collapsible, tube-like member having a lumen
extending therethrough, the first and second restrictor each being
formed over a portion of the flexible membrane.
40-72. (canceled)
73. A medical method, comprising: at least partially implanting a
catheter shaft within a vein of a patient, thereby positioning a
first restrictor coupled to the catheter shaft at a location that
is upstream of an outflow port of a duct of the patient's lymphatic
system and positioning a second restrictor coupled to the catheter
shaft at a location that is downstream of the outflow port of the
duct, the catheter shaft having a pump coupled thereto; after the
first restrictor is positioned, actuating the first restrictor to
move the first restrictor from a relaxed configuration to an
activated configuration; after the second restrictor is positioned,
actuating the second restrictor to move the second restrictor from
a relaxed configuration to an activated configuration; after the
first and second restrictors are actuated, actuating the pump to
cause a low pressure zone to be created along the catheter between
the first and second restrictors.
74-86. (canceled)
Description
CROSS REFERENCE
[0001] The present application claims priority to U.S. Provisional
Patent Application No. 62/159,465 entitled "System And Method For
Treatment Of Pulmonary Edema" filed May 11, 2015 and to U.S.
Provisional Patent Application No. 62/233,802 entitled "Systems And
Methods For Reducing Pressure At An Outflow Of A Duct" filed Sep.
28, 2015, which are hereby incorporated by reference in their
entireties.
FIELD
[0002] The present disclosure relates generally to systems and
methods for reducing pressure at an outflow of a duct.
BACKGROUND
[0003] The lymphatic system is part of the circulatory system in
conjunction with the arterial and venous systems. A primary
function of the lymphatic system is to drain excessive interstitial
fluid back into the venous system at two main locations: the
thoracic duct and the lymphatic duct, which drain into the left and
right subclavian veins, respectively.
[0004] Under normal circulatory conditions of the arterial and
venous systems the interstitial fluid volume balance is maintained
and the lymph fluid is cleared back through the lymphatic system.
In pathological conditions such as Acute Cardiogenic Pulmonary
Edema and chronic heart failure, the capillary hydrostatic pressure
and the venous pulmonary pressure can become elevated and fluid
flows excessively out of the blood vessels and into the
interstitial and alveolar spaces. The pressure gradient between the
initial lymphatics and at the outflow of the thoracic duct and the
lymphatic duct is reduced and the lymphatic system cannot clear the
additional fluid which accumulates in the air spaces of the lungs.
This is a life threatening condition as gas exchange is impaired to
the extent that it may lead to respiratory failure.
[0005] Current treatment methods require extended hospitalization
and treatment with loop diuretics and/or vasodilators. Oftentimes
patients must also receive supplemental oxygen or, in more extreme
cases, require mechanical ventilation. Many of these treatment
methods are less than ideal because the edema is not always
alleviated rapidly enough and for many patients renal function is
adversely affected. A significant percentage of patients do not
respond to this treatment and a significant percentage must be
readmitted to a hospital within thirty days.
[0006] A significant problem with current treatment protocol is
that it is based on the need to reduce intravascular blood pressure
to move interstitial and lymphatic fluid back into the vasculature.
The reduction of intravascular blood pressure may lead to
hypotension and may activate the Renin Angiotenesin Aldesterone
System, which may lead back to an increase in blood pressure or to
worsening of renal function. Eventually, this cycle leads to
diuretic resistance and the worsening of renal function in almost
30% of admitted patients. The lymphatic system can directly drain
fluids from the interstitial compartment into the intravascular
compartment and by such to relief edema.
[0007] The lymphatic system drains the interstitial fluids via the
thoracic duct and right lymphatic duct that drain into the region
around the bifurcation of the left subclavian vein and left
internal jugular vein for the thoracic duct and into the
bifurcation of the right internal jugular vein and right subclavian
vein for the right lymphatic duct. However, in conditions such as
acutely decompensated heart failure the lymphatic return is reduced
as a result of elevated central venous pressure (CVP). Therefore,
as a result of the elevated CVP, the lymphatic return is greatly
reduced.
[0008] Accordingly, there remains a need for improved systems and
methods for reducing pressure at an outflow of a duct such as the
thoracic duct or the lymphatic duct.
SUMMARY
[0009] Various devices, methods, and systems are provided for
treating edema. An indwelling catheter configured to be implantable
within a vein of a patient is provided that in one embodiment
includes a sheath at least partially implantable within a patient's
vein. The sheath has a lumen extending therethrough and a catheter
shaft movably positioned within and extending through the lumen of
the sheath. The indwelling catheter also includes a catheter shaft
movably positioned within and extending through the lumen of the
sheath. The catheter shaft is configured to be at least partially
implantable within a patient's vein and a proximal end can extend
from a proximal end of the sheath and a distal end can extend from
a distal end of the sheath. The catheter shaft has a suction lumen
extending therethrough, and one or more suction ports disposed
therein and in fluid communication with the suction lumen. The
indwelling catheter also includes a flexible membrane attached to a
distal portion of the catheter shaft. The flexible membrane is a
collapsible, tube-like member having a lumen extending
therethrough. The indwelling catheter also includes a selectively
deployable restriction member formed over a portion of the flexible
membrane, and an inflation lumen extending through the catheter
shaft. The at least one inflation lumen is in fluid communication
with the restriction member.
[0010] The indwelling catheter also includes can vary in any number
of ways. For example, the indwelling catheter can include a cone
shaped tip at the distal end of the catheter shaft. For another
example, the flexible membrane can be coupled to an outer wall of
the catheter shaft along a length of the flexible membrane. The
flexible membrane can be bonded or welded to the catheter shaft
along one or several segments and along about 10 to 360 degrees of
a circumference of the catheter shaft, e.g., along about 180 to 270
degrees of a circumference of the catheter shaft.
[0011] For yet another example, the flexible membrane can be
oriented so as to be substantially parallel to the catheter shaft.
For still another example, the restriction member can be a
selectively expandable balloon coupled to an outer wall of the
flexible membrane.
[0012] For another example, the indwelling catheter can include a
second selectively deployable restriction member formed over a
distal portion of the flexible membrane. The restriction member can
be formed over a proximal portion of the flexible membrane, and the
at least one inflation lumen can be in fluid communication with the
second restriction member. The second selectively deployable
restriction member can be a selectively expandable balloon coupled
to an outer wall of the flexible membrane. The indwelling catheter
can include a first pressure port disposed proximally of the
restriction member, and a second pressure port disposed between the
selectively deployable restriction members. Instead of using
pressure ports, a miniature pressure sensor can be mounted on the
catheter at the same locations. For yet another example, the
indwelling catheter can include a first pressure port disposed
distally to the second restriction member, and a second pressure
port disposed between the selectively deployable restriction
members. Instead of using pressure ports, a miniature pressure
sensor can be mounted on the catheter at the same locations. For
another example, the indwelling catheter can include a first
pressure port disposed proximally of the restriction member, a
second pressure port disposed between the selectively deployable
restriction members, and a third pressure port disposed distally to
the second restriction member. Instead of using pressure ports, a
miniature pressure sensor can be mounted on the catheter at the
same locations.
[0013] For yet another example, the indwelling catheter can include
a first inflation port disposed in an outer wall of the flexible
membrane and in fluid communication with the first selectively
deployable restriction member. The indwelling catheter can further
include a second inflation port disposed on the outer wall of the
flexible member and in fluid communication with the second
selectively deployable restriction member.
[0014] In another aspect, a method of treating edema is provided
that in one embodiment includes advancing from a sheath implanted
within a vein of a patient a catheter shaft having a flexible and
collapsible tubular membrane coupled to an outer wall of the
catheter shaft at a distal portion thereof, so as to position the
catheter shaft within the vein such that a distal end of the
catheter shaft is positioned distally of at least one outflow port
of a duct of the lymphatic system. The method also includes
actuating a first expandable member attached to the membrane to
create a first restriction within the vein adjacent to a proximal
region of the flexible membrane of the catheter shaft. The first
restriction is positioned proximally of the at least one outflow
port. The method also includes actuating a second expandable member
attached to the membrane to create a second restriction within the
vein distal to the first restriction and adjacent to a distal
region of the flexible membrane of the catheter shaft. The second
restriction is positioned distally of the at least one outflow
port. The first and second restriction members create a localized
low pressure zone extending therebetween.
[0015] The method can have any number of variations. For example,
the method can include implanting the sheath of the catheter system
within the vein of the patient.
[0016] For another example, the method can include withdrawing
fluid from within the low pressure zone through the catheter to a
pump and returning fluid to a vein such that the returned fluid
passes through the membrane to bypass the low pressure zone.
Withdrawing fluid can be accomplished by passing fluid from within
the low pressure zone through a suction port disposed in a wall of
the catheter shaft and in fluid communication with the low pressure
zone between the first and second restrictions. The suction port
can be in communication with a suction tubing line of the catheter
to withdraw fluid from the vein through an action of the pump and
return fluid to venous circulation through the suction tubing line
coupled to a proximal end of the catheter sheath wherein the fluid
is discharged at a distal end of the catheter sheath proximal to
the first restriction. The catheter can be implanted in one of the
right and left internal jugular veins and advanced to a position
such that the second restriction is distal to a junction of a
subclavian vein and an internal jugular vein, the first restriction
can be within the internal jugular vein, and the second restriction
can be within an innominate vein and the suction port is adjacent
to the junction of the subclavian vein. The catheter can be
implanted in one of the right and left internal jugular veins and
advanced to a position such that the second restriction is distal
to a junction of a subclavian vein and an internal jugular vein,
and the first restriction can be within the internal jugular vein,
the second restriction can be within an innominate vein, and the
suction port can be adjacent to the junction of the subclavian
vein. The catheter can be implanted in one of the right and left
internal jugular veins and advanced to a position such that the
second restriction is distal to a junction of both innominate
veins, and the first restriction can be within the internal jugular
vein, the second restriction can be within a superior vena cava
(SVC) vein (also referred to as an innominate vein), and the
suction port can be adjacent to a junction of the subclavian
vein.
[0017] For yet another example, transporting the fluid through the
localized low pressure zone via the flexible membrane can maintain
a constant pressure within the low pressure zone.
[0018] In another aspect, a system for treating edema is provided
that in one embodiment includes an indwelling catheter system
configured for at least partial placement within a vein of a
patient. The indwelling catheter system has an implantable sheath
with a lumen extending therethrough, and a catheter shaft movably
positioned within and extending through the lumen of the sheath.
The catheter shaft has one or more suction ports disposed therein.
The indwelling catheter system also has a flexible membrane
attached to a distal portion of the catheter shaft, a first
selectively deployable restriction member formed over a proximal
portion of the flexible membrane, and a second selectively
deployable restriction member formed over a distal portion of the
flexible membrane and an inflation lumen extending through the
catheter shaft. The inflation lumen is in fluid communication with
the first and the second restriction members. The system for
treating edema further includes a pump configured to create a
pressure differential to withdraw fluid from the suction port and
through a suction lumen from the catheter shaft to withdraw a fluid
within the vein from venous circulation and to return the fluid to
venous circulation through the catheter system, a plurality of
pressure sensors disposed within the catheter system, and a control
module configured to control operation of the system.
[0019] The system for treating edema can have any number of
variations. For example, the system for treating edema can include
a pump configured to be external to the patient. For another
example, the pump can be a peristaltic flow pump.
[0020] Various systems and methods are provided for reducing
pressure at an outflow of a duct such as the thoracic duct or the
lymphatic duct. A medical system is provided that in one embodiment
includes a catheter shaft configured to be positioned within a vein
of a patient, a first selectively deployable restrictor coupled to
the catheter shaft and configured to be positioned within the vein,
a second selectively deployable restrictor coupled to the catheter
shaft at a location distal to the first restrictor such that a
distance spans between the first and second restrictors, at least
one inlet opening formed through a sidewall of the catheter shaft
at a location between the first and second restrictors, and a pump
configured to facilitate suction of fluid into the catheter shaft
through the at least one inlet opening. The second restrictor is
configured to be positioned within the vein.
[0021] The medical system can have any number of variations. For
example, the first and second restrictors can each include a
balloon. The medical system can include at least one inflation
lumen extending along the catheter shaft. The at least one
inflation lumen can be in fluid communication with the first and
second restrictors. The at least one inflation lumen can include a
single lumen in fluid communication with both of the first and
second restrictors, or the at least one inflation lumen can include
a first inflation lumen in fluid communication with the first
restrictor and a second inflation lumen in fluid communication with
the second restrictor.
[0022] For another example, the first restrictor can be movable
between an activated configuration in which the first restrictor
has a first diameter and a relaxed configuration in which the first
restrictor has a second diameter that is less than the first
diameter, and the second restrictor can be movable between an
activated configuration in which the second restrictor has a third
diameter and a relaxed configuration in which the second restrictor
has a fourth diameter that is less than the third diameter. The
first diameter can be equal to the third diameter, or the first
diameter can be less than the third diameter.
[0023] For yet another example, the first and second restrictors
can each include a stent. For still another example, the medical
system can include at least one additional inlet opening formed
through the sidewall of the catheter shaft at a location that is
proximal to the first and second restrictors. For another example,
the catheter shaft can have an open distal end. For yet another
example, the pump can include an impeller within the catheter
shaft. For another example, the pump can be configured to be
positioned within the vein, or the pump can be non-implantable. For
still another example, the medical system can include at least one
sensor.
[0024] For another example, the medical system can include a
controller configured to actuate the pump. The controller can be
configured to actuate the pump in response to user operation of a
control external to the body of the patient. The medical system can
include a pressure sensor configured to be implanted in the body of
the patient, and the controller can be configured to actuate the
pump in response to a pressure measured by the pressure sensor
exceeding a predefined threshold and/or the controller can be
configured to control a speed of operation of the pump depending on
a pressure measured by the pressure sensor.
[0025] For yet another example, the medical system can include a
flexible membrane attached to a distal portion of the catheter
shaft. The flexible membrane can be a collapsible, tube-like member
having a lumen extending therethrough. The first and second
restrictor can each be formed over a portion of the flexible
membrane.
[0026] For another example, the vein can include an internal
jugular vein or a subclavian vein.
[0027] In another aspect, a medical method is provided that can
include implanting the catheter shaft at least at least partially
within a vein of a patient such that the first restrictor is
positioned upstream of an outflow port of a duct of the patient's
lymphatic system and such that the second restrictor is positioned
downstream of the outflow port of the duct.
[0028] The medical method can vary in any number of ways. For
example, the medical method can include activating the first
restrictor of the medical system such that the first restrictor
occludes the vein at a first occlusion site, and activating the
second restrictor such that the second restrictor occludes the vein
at a second occlusion site. Activating the first restrictor can
include inflating the first restrictor, and activating the second
restrictor can include inflating the second restrictor, and/or
activating the first restrictor can include radially expanding the
first restrictor, and activating the second restrictor can include
radially expanding the second restrictor. For another example, the
medical method can include actuating the pump, thereby creating a
low pressure zone between the first and second restrictors. For yet
another example, the duct can include a thoracic duct. For still
another example, the duct can include a lymphatic duct. For another
example, the vein can include an internal jugular vein or a
subclavian vein.
[0029] In another embodiment, a medical system is provided that
includes a catheter shaft configured to be positioned within a vein
of a patient, and at least one restrictor coupled to the catheter
shaft and configured to be positioned within the vein. The at least
one restrictor is movable between an activated configuration in
which the at least one restrictor has a first diameter and a
relaxed configuration in which the at least one restrictor has a
second diameter that is less than the first diameter. The at least
one restrictor is configured to occlude fluid flow through the vein
when the at least one restrictor is in the activated configuration
within the vein. The medical system also includes a pump configured
to pump fluid through the catheter shaft regardless of whether the
at least one restrictor is in the activated configuration or the
relaxed configuration.
[0030] The medical system can have any number of variations. For
example, the at least one restrictor includes a single restrictor.
For another example, the at least one restrictor can include first
and second restrictors. The second restrictor can be coupled to the
catheter shaft at a location distal to the first restrictor such
that a distance spans between the first and second restrictors.
[0031] For yet another example, the at least one restrictor can
include a balloon. The medical system can include at least one
inflation lumen extending along the catheter shaft. The at least
one inflation lumen can be in fluid communication with the at least
one restrictor.
[0032] For still another example, the at least one restrictor can
include a stent. For yet another example, the pump can include an
impeller within the catheter shaft. For another example, the pump
can be configured to be positioned within the vein, or the pump can
be non-implantable. For still another example, the medical system
can include at least one sensor.
[0033] For yet another example, the medical system can include a
controller configured to actuate the pump. The controller can be
configured to actuate the pump in response to user operation of a
control external to the body of the patient. The medical system can
include a pressure sensor configured to be implanted in the body of
the patient, and the controller can be configured to actuate the
pump in response to a pressure measured by the pressure sensor
exceeding a predefined threshold and/or can be configured to
control a speed of operation of the pump depending on a pressure
measured by the pressure sensor.
[0034] For still another example, the medical system can include a
flexible membrane attached to a distal portion of the catheter
shaft. The flexible membrane can be a collapsible, tube-like member
having a lumen extending therethrough. The at least one restrictor
can be formed over a portion of the flexible membrane.
[0035] For another example, the vein can include an internal
jugular vein or a subclavian vein.
[0036] In another aspect, a medical method is provided that
includes implanting the catheter shaft of the medical system at
least at least partially within a vein of a patient such that the
at least one restrictor is positioned upstream of an outflow port
of a duct of the patient's lymphatic system.
[0037] The medical method can have any number of variations. For
example, the medical method can include activating the at least one
restrictor such that the at least one restrictor occludes the vein.
Activating the at least one restrictor can include inflating the at
least one restrictor and/or radially expanding the at least one
restrictor.
[0038] For another example, the medical method can include
actuating the pump, thereby creating a low pressure zone adjacent
the duct. For yet another example, the duct can include a thoracic
duct. For still another example, the duct can include a lymphatic
duct. For another example, the vein can include an internal jugular
vein or a subclavian vein.
[0039] In another embodiment, a medical method is provided that
includes at least partially implanting a catheter shaft within a
vein of a patient, thereby positioning a first restrictor coupled
to the catheter shaft at a location that is upstream of an outflow
port of a duct of the patient's lymphatic system and positioning a
second restrictor coupled to the catheter shaft at a location that
is downstream of the outflow port of the duct. The catheter shaft
has a pump coupled thereto. The medical method also includes, after
the first restrictor is positioned, actuating the first restrictor
to move the first restrictor from a relaxed configuration to an
activated configuration. The medical method also includes, after
the second restrictor is positioned, actuating the second
restrictor to move the second restrictor from a relaxed
configuration to an activated configuration. The medical method
also includes, after the first and second restrictors are actuated,
actuating the pump to cause a low pressure zone to be created along
the catheter between the first and second restrictors.
[0040] The medical method can vary in any number of ways. For
example, actuating the first restrictor can include inflating the
first restrictor, and actuating the second restrictor can include
inflating the second restrictor. For another example, actuating the
first restrictor can include radially expanding the first
restrictor, and actuating the second restrictor can include
radially expanding the second restrictor. For yet another example,
the medical method can include, after the pump is actuated,
re-actuating the first restrictor to move the first restrictor from
the activated configuration to the relaxed configuration, and
re-actuating the second restrictor to move the second restrictor
from the activated configuration to the relaxed configuration.
After re-actuating the first and second restrictors, the catheter
shaft and the first and second restrictors can be removed from the
patient.
[0041] For still another example, the pump can be actuated in
response to user operation of a control external to the body of the
patient. For another example, the pump can be actuated periodically
or continuously. For yet another example, the duct can include a
thoracic duct of the patient. For still another example, the duct
can include a lymphatic duct of the patient. For another example,
the vein can include an internal jugular vein of the patient or a
subclavian vein of the patient.
[0042] For yet another example, the medical method can include
implanting a pressure sensor in a location within the body of the
patient that enables the pressure sensor to measure pressure in a
desired region of the body of the patient. The medical method can
include measuring the pressure in the desired region using the
pressure sensor, and actuating the pump in response to the measured
pressure exceeding a predefined threshold and/or controlling a
speed of operation of the pump depending on the measured
pressure.
BRIEF DESCRIPTION OF DRAWINGS
[0043] This invention will be more fully understood from the
following detailed description taken in conjunction with the
accompanying drawings, in which:
[0044] FIG. 1 is a schematic cross-sectional view of one embodiment
of a catheter implanted in a vein of a patient;
[0045] FIG. 2 is a perspective, partially transparent view of a
distal portion of another embodiment of a catheter;
[0046] FIG. 3 is a perspective, partially transparent view of a
distal portion of yet another embodiment of a catheter;
[0047] FIG. 4 is a partial cross-sectional view of the distal
portion of the catheter of FIG. 3;
[0048] FIG. 5 is a cross-sectional view of the distal portion of
the catheter of FIG. 3;
[0049] FIG. 6 is a schematic version of the cross-sectional view of
FIG. 5;
[0050] FIG. 7 is a perspective, partially transparent view of a
distal portion of yet another embodiment of a catheter;
[0051] FIG. 8 is a partial cross-sectional view of the distal
portion of the catheter of FIG. 7;
[0052] FIG. 9 is a schematic version of the cross-sectional view of
FIG. 8;
[0053] FIG. 10 is a perspective view of one embodiment of a
catheter system;
[0054] FIG. 10A is perspective view of a flexible membrane and
catheter shaft of the catheter system of FIG. 10;
[0055] FIG. 10B is another perspective view of the flexible
membrane and catheter shaft of the catheter system of FIG. 10A;
[0056] FIG. 10C is a perspective view of a restrictor of the
catheter system of FIG. 10 attached to the flexible membrane of the
catheter system;
[0057] FIG. 10D is side, partial cross-sectional view of flattened
edges of the restrictor of FIG. 10A;
[0058] FIG. 10E is a side, partial cross-sectional view of folded
edges of another embodiment of a restrictor;
[0059] FIG. 10F is a cross-sectional schematic view of one
embodiment of a pattern for forming a restriction member with a
torus shape;
[0060] FIG. 10G is cross-sectional schematic view of one embodiment
of a restriction member formed using the pattern of FIG. 10F and
one embodiment of a sleeve on which the restriction member is
assembled;
[0061] FIG. 10H is a cross-sectional schematic view of the
restriction member of FIG. 10G following inversion of legs
thereof;
[0062] FIG. 11A is a perspective view of a distal portion of the
catheter system of FIG. 10;
[0063] FIG. 11B is a side view of another distal portion of the
catheter system of FIG. 10;
[0064] FIG. 12A is a perspective view of a proximal portion of the
catheter system of FIG. 10;
[0065] FIG. 12B is a side view of the catheter system of FIG.
10;
[0066] FIG. 13 is a distal end view of the catheter system of FIG.
10;
[0067] FIG. 14 is a cross sectional view of the catheter system of
FIG. 10 with a flexible membrane of the catheter system in an
expanded configuration;
[0068] FIG. 15 is a cross sectional view of the catheter system of
FIG. 10 having a restrictor thereof in an activated
configuration;
[0069] FIG. 16 is a cross sectional view of the catheter system of
FIG. 10 having a restrictor thereof in a relaxed configuration;
[0070] FIG. 17A is a schematic, partially cross-sectional view of a
portion of the catheter system of FIG. 10 implanted in a
patient;
[0071] FIG. 17B is a perspective, partially cross-sectional view of
another portion of the catheter system of FIG. 17A implanted in the
patient;
[0072] FIG. 17C is another perspective, partially cross-sectional
view of the catheter system of FIG. 17A implanted in the
patient;
[0073] FIG. 18 is a side cross-sectional view of a distal portion
of the catheter system of FIG. 10;
[0074] FIG. 19 is a cross-sectional view of the distal portion of
the catheter system of FIG. 18;
[0075] FIG. 20 is a schematic, partially cross-sectional view of a
distal portion of the catheter system of FIG. 10 introduced into a
vein;
[0076] FIG. 21 is a schematic diagram of one embodiment of a
control module;
[0077] FIG. 22 is a front view of one embodiment of the control
module of FIG. 21;
[0078] FIG. 23 is a perspective partially cross-sectional view of a
distal portion of one embodiment of a catheter system advanced into
a body of a patient;
[0079] FIG. 24 is a perspective partially cross-sectional view of a
catheter of the catheter system of FIG. 23 advanced distally out of
a sheath of the catheter system with restrictors of the catheter
being in a collapsed configuration;
[0080] FIG. 25 is a perspective partially cross-sectional view of
the sheath and catheter of FIG. 24 with the restrictors in an
expanded configuration;
[0081] FIG. 26 is a perspective partially cross-sectional view of
the catheter of FIG. 25 with a pump of the catheter system
suctioning blood through the catheter;
[0082] FIG. 26A is side partially cross-sectional view of the
catheter of FIG. 26;
[0083] FIG. 27 is a perspective partially cross-sectional view of
the catheter of FIG. 26 with the pump of the catheter system
suctioning blood through the catheter and discharging blood into
the sheath;
[0084] FIG. 28 is a perspective partially cross-sectional view of
the catheter of FIG. 27; and
[0085] FIG. 29 is a flow diagram for one embodiment of operation of
a control module for a system of treating edema.
DETAILED DESCRIPTION
[0086] Certain exemplary embodiments will now be described to
provide an overall understanding of the principles of the
structure, function, manufacture, and use of the devices and
methods disclosed herein. One or more examples of these embodiments
are illustrated in the accompanying drawings. Those skilled in the
art will understand that the devices and methods specifically
described herein and illustrated in the accompanying drawings are
non-limiting exemplary embodiments and that the scope of the
present invention is defined solely by the claims. The features
illustrated or described in connection with one exemplary
embodiment may be combined with the features of other embodiments.
Such modifications and variations are intended to be included
within the scope of the present invention.
[0087] Reference throughout the specification to "various
embodiments," "some embodiments," "one embodiment," or "an
embodiment," or the like, means that a particular feature,
structure, or characteristic described in connection with the
embodiment is included in at least one embodiment. Thus,
appearances of the phrases "in various embodiments," "in some
embodiments," "in one embodiment," or "in an embodiment," or the
like, in places throughout the specification are not necessarily
all referring to the same embodiment. Furthermore, the particular
features, structures, or characteristics may be combined in any
suitable manner in one or more embodiments. Thus, the particular
features, structures, or characteristics illustrated or described
in connection with one embodiment may be combined, in whole or in
part, with the features structures, or characteristics of one or
more other embodiments without limitation.
[0088] It will be appreciated that the terms "proximal" and
"distal" may be used throughout the specification with reference to
a clinician manipulating one end of an instrument used to treat a
patient. The term "proximal" refers to the portion of the
instrument closest to the clinician and the term "distal" refers to
the portion located furthest from the clinician. It will be further
appreciated that for conciseness and clarity, spatial terms such as
"vertical," "horizontal," "up," and "down" may be used herein with
respect to the illustrated embodiments. However, surgical
instruments may be used in many orientations and positions, and
these terms are not intended to be limiting and absolute.
[0089] Further, in the present disclosure, like-named components of
the embodiments generally have similar features, and thus within a
particular embodiment each feature of each like-named component is
not necessarily fully elaborated upon. Additionally, to the extent
that linear or circular dimensions are used in the description of
the disclosed systems, devices, and methods, such dimensions are
not intended to limit the types of shapes that can be used in
conjunction with such systems, devices, and methods. A person
skilled in the art will recognize that an equivalent to such linear
and circular dimensions can easily be determined for any geometric
shape. Sizes and shapes of the systems and devices, and the
components thereof, can depend at least on the anatomy of the
subject in which the systems and devices will be used, the size and
shape of components with which the systems and devices will be
used, and the methods and procedures in which the systems and
devices will be used.
[0090] Various systems and methods are provided for reducing
pressure at an outflow of a duct such as the thoracic duct or the
lymphatic duct. In general, the systems and methods may be
effective to reduce edema conditions, such as pulmonary edema, in a
patient by lowering an outflow pressure in a region around the
patient's thoracic/lymphatic duct outflow. As a result of lowering
the outflow pressure at the thoracic and/or lymphatic ducts, higher
lymphatic return will be achieved, enabling the lymphatic vessel
flow to be at or near normal levels. The systems and methods may be
effective to rapidly alleviate conditions of the edema and increase
the patient response rate. In an exemplary embodiment, the systems
and methods may be particularly useful to treat acute pulmonary
edema, however a person skilled in the art will appreciate that the
systems and methods can be used in various procedures for treating
a lymphatic system fluid clearance imbalance.
[0091] In one embodiment, an indwelling catheter can be configured
to be at least partially implanted (e.g., partially implanted or
fully implanted) within a vein of a patient in the vicinity of an
outflow port of a duct of the lymphatic system, e.g., in the
vicinity of an outflow port of the thoracic duct or in the vicinity
of an outflow port of the lymphatic duct. Exemplary materials from
which the catheter can be made include polyurethanes. The catheter
can include first and second restrictors (also referred to herein
as "restriction members") each configured to at least partially
occlude the vein within which the catheter is implanted and thus to
restrict fluid flow within the vein when the restrictors are
activated. The restrictors can each be configured to move between
an activated configuration, in which the restrictor occludes the
vein, and a relaxed configuration, in which the restrictor does not
occlude the vein. The restrictors can each be in the relaxed
configuration during implantation of the catheter to ease
introduction of the catheter into the patient's body and into the
vein. Each of the restrictors can include a balloon configured to
be inflated where in the relaxed configuration the balloon is not
inflated and in the activated configuration in which the balloon is
inflated. The restrictors can be made from any one or more of a
variety of materials configured to expand upon the delivery of a
fluid thereto and to contract upon the withdrawal of the fluid.
Exemplary materials from which the balloon can be made include
polymeric materials such as PEBAX, silicones, polyurethanes, and
nylons. The catheter can include at least one inflation lumen
through which an inflation fluid (e.g., air, liquid, etc.) can be
introduced to inflate/deflate the restrictors. The at least one
inflation lumen can include one lumen in fluid communication with
both of the restrictors such that the restrictors can be
simultaneously inflated/deflated, or can include first and second
lumens with the first lumen in fluid communication with the first
restrictor and the second lumen in fluid communication with the
second restrictor such that the restrictors can be selectively
inflated simultaneously or sequentially. The catheter can include a
pump, such as an axial motor pump, configured to pump fluid through
the catheter. The catheter can be coupled to a motor configured to
drive the pump. The motor can be included in the catheter (e.g.,
within a shaft of the catheter) and be configured to be implanted
with the catheter, or the motor can be located outside of the
catheter (e.g., outside of the catheter's shaft) and be configured
to be located outside of the patient rather than be implanted
therein.
[0092] In one embodiment of using the catheter, the catheter can be
positioned at a desired location within the vein. The first and
second restrictors can then each be activated (simultaneously or
sequentially) to move from the relaxed configuration to the
activated configuration. The first and the second restrictors, when
activated so as to provide two occlusions within the vein, define a
low pressure zone therebetween within a portion of the vein in
which the catheter is positioned. Higher pressure zones accordingly
exist on either side of the restrictors. The motor can drive the
pump to induce the low pressure zone by causing fluid to be pumped
through the catheter. The catheter and the restrictors can be
positioned within the vein such that the low pressure zone is
adjacent to an outflow port of a duct (e.g., the thoracic duct or
the lymphatic duct) to allow fluid to pass from the lymph duct
outflow port to the portion of the catheter housed within the vein
so that fluid can flow out of the catheter.
[0093] In at least some embodiments, the restrictor(s) of a
catheter can be inflated and deflated from time to time to enable
free flow of blood in a patient's vein in which the restrictor(s)
are positioned and thus enable the system to stop working for a
period of time. This period of time can be required in such
treatments to allow for the assessment of the patient's clinical
condition, allow the patient to undergo other treatments or enable
him to go to the bathroom and/or to wash any stagnation points that
might have occurred.
[0094] The catheters described herein can be configured to be
placed in a patient's body for up to about seventy-two hours, e.g.,
the catheter can be indwelled in the body for up to about
seventy-two hours. The catheter systems described herein that
include the catheters can be operated in a treatment time period in
a range of about 6 to 8 hours. At the end of each treatment period,
the restrictors are deflated, the catheter can be filled with a
heparin catheter locking solution, and an assessment of the
patient's clinical condition can be performed. The catheter system
can be operated again if desired by medical personnel. Within the
indwelling period of the catheter, a number of treatment periods
can be in a range of 3 to 6 cycles, e.g., for a maximum of about
forty hours of operation within a seventy-two hour indwelling
period.
[0095] A person skilled in the art will appreciate that the systems
and methods disclosed herein can be used with a variety of surgical
devices, including measuring devices, sensing devices, locator
devices, insertion devices, etc.
[0096] FIG. 1 illustrates one embodiment of a catheter 1 that
includes at least one restrictor 2a, 2b. The at least one
restrictor includes first and second restrictors 2a, 2b in this
illustrated embodiment, which each include a balloon configured to
be inflated (corresponding to an activated configuration) and
deflated (corresponding to a relaxed configuration). The first and
second restrictors 2a, 2b can be spaced a distance apart from one
another along a longitudinal length of the catheter 1 such that one
of the restrictors 2b is more distal than the other of the
restrictors 2a. The distance between the first and second
restrictors 2a, 2b can define a length of a low pressure zone that
can be created when the catheter 1 is implanted within a vein. FIG.
1 shows the catheter 1 positioned within an internal jugular vein 3
of a patient with the distal restrictor 2b positioned distal to an
outflow port 4p of the patient's thoracic duct 4 and the proximal
restrictor 2a positioned proximal to the outflow port 4p of the
patient's thoracic duct 4. The low pressure zone defined between
the proximal and distal (first and second) restrictors 2a, 2b can
thus be located adjacent the outflow port 4p of the thoracic duct
4. The proximal restrictor 2a being positioned proximal to (e.g.,
upstream) of the outflow port 4p of the thoracic duct 4 may help
prevent back flow from the patient's subclavian vein 5 while
providing the low pressure zone and benefit(s) thereof. The
catheter 1 can be similarly positioned on a right side of the
patient with the distal restrictor 2b positioned distal to an
outflow port of the patient's subclavian vein 5 and an outflow port
of the patient's lymphatic duct (not shown) and the proximal
restrictor 2a positioned proximal to the outflow port of the
patient's subclavian vein 5 and the outflow port of the patient's
lymphatic duct.
[0097] The catheter 1 can include at least one inflation lumen
(omitted from FIG. 1 for clarity of illustration) configured to
facilitate inflation of the first and second restrictors 2a, 2b,
e.g., to facilitate movement of the restrictors 2a, 2b between the
activated and relaxed configurations. The first and second
restrictors 2a, 2b are shown in the activated configuration in FIG.
1 with the first and second restrictors 2a, 2b each abutting an
internal surface of the jugular vein 3 so as to provide two,
spaced-apart occlusions therein.
[0098] The catheter 1 can include a shaft 7 having a lumen 7L, as
shown in this illustrated embodiment, configured to communicate
fluid therethrough so as to accommodate the flow of fluid in a vein
in which the catheter 1 is implanted. The shaft 7 can have a
variety of sizes, such as having a diameter that is in the range of
about 8 to 18 Fr (e.g., about 8 Fr, equal to or less than about 12
Fr, etc.) and having a length in the range of about 25 to 40
cm.
[0099] The first and second restrictors 2a, 2b can be attached to
and surround the shaft 7. The first and second restrictors 2a, 2b
can each be formed in the shape of a torus, as in this illustrated
embodiment, to facilitate the surrounding of the shaft 1 and/or to
help prevent compression of the restrictors 2a, 2b when they are
moved radially outward during expansion thereof and thereby thus
overcoming a possible tendency for the restrictors 2a, 2b to
collapse in response to an external pressure. The first and second
restrictors 2a, 2b can, however, have other shapes.
[0100] The catheter 1 can have a first or distal suction inlet 8d
formed through the shaft's sidewall. The distal suction inlet can
be in communication with the lumen 7L so as to allow fluid to enter
the lumen 7L therethrough, as shown in FIG. 1 by four arrows at the
distal suction inlet 8d pointing inward toward the lumen 7L. The
distal suction inlet 8d can include any number of openings formed
through the shaft's sidewall. The openings can have any of a
variety of configurations, e.g., slits, circular holes, ovular
holes, rectangular slots, etc. The distal suction inlet 8d can be
located along the catheter's longitudinal length at a position
between the first and second restrictors 2a, 2b. The distal suction
inlet 8d can thus be located within the low pressure zone. In an
exemplary embodiment, as shown in FIG. 1, in use, the distal
suction inlet 8d can be positioned adjacent the outflow ports 4p,
5p of the thoracic duct 4 and the subclavian vein 5 so as to allow
fluid exiting the outflow ports 4p. 5p to enter the catheter 1.
[0101] The catheter 1 can include a second or proximal suction
inlet 8p formed through the shaft's sidewall. The proximal suction
inlet 8p can be in communication with the lumen 7L so as to allow
fluid to enter the catheter's lumen 7L therethrough, as shown in
FIG. 1 by two arrows at the proximal suction inlet 8p pointing
inward toward the lumen 7L. The proximal suction inlet 8p can
include any number of openings formed through the shaft's sidewall.
The openings can have any of a variety of configurations, e.g.,
slits, circular holes, ovular holes, rectangular slots, etc. The
proximal suction inlet 8p can be located proximal to the distal
suction inlet 8d and proximal to the first and second restrictors
2a, 2b. In an exemplary embodiment, as shown in FIG. 1, in use, the
proximal suction inlet 8p can be positioned proximal to the outflow
ports 4p, 5p of the thoracic duct 4 and the subclavian vein 5,
e.g., upstream thereof. The proximal suction inlet 8p may thus
allow for regular fluid flow through the jugular vein 3 even when
the proximal restrictor 2a is activated and occluding the jugular
vein 3.
[0102] The catheter 1 can include a distal end 1d configured to be
implanted within the patient's body (e.g., within the jugular vein
3, as shown in this illustrated embodiment) and a proximal end 1p
configured to not be implanted and instead be located outside the
patient's body when the catheter's distal end 1d is implanted. The
distal end 1d of the catheter 1 can be open so as to define a
discharge opening of the catheter 1 that allows fluid in the lumen
7L to exit the catheter 1 therethrough. The distal restrictor 2b
being positioned proximal to the discharge opening may help prevent
back flow of fluid exiting the catheter 1 through the discharge
opening. The distal restrictor 2b can thus be positioned just
proximal to the discharge opening to help maximize backflow
prevention. The catheter's proximal end 1p is configured to not be
implanted and is shown outside of the patient's body in FIG. 1.
FIG. 1 also shows a controller or motor 9 coupled to the catheter 1
and located outside of and proximal to the catheter's proximal end
1p so as to not be within the catheter's shaft 7 and to be located
outside of the patient's body. Alternatively, as mentioned above,
the catheter's proximal end 1p can be configured to be implanted,
such as when the controller or motor 9 is included in the
catheter's shaft 7.
[0103] The catheter 1 can include a pump configured to drive fluid
flow through the catheter 1, e.g., through the lumen 7L thereof.
The pump can have a variety of configurations. As in this
illustrated embodiment, the pump can include an axial motor pump.
The axial motor pump can generally be configured like an
Archimedes' screw that drives fluid. The axial motor pump can
include an impeller I and a drive shaft S (e.g., a cable or a rod)
each located in the catheter's shaft 7, e.g., in the lumen 7L. Also
as in this illustrated embodiment, the impeller I can be located
fully distal to the proximal restrictor 2a and can be located at
least partially proximal to the second restrictor 2b so as to be at
least partially located within the low pressure zone and hence near
the distal inlet opening. In this illustrated embodiment, the
impeller I is fully located within the low pressure zone. The drive
shaft S can extend longitudinally through the catheter 1, e.g.,
through the lumen 7L, to the controller or motor 9. The motor 9 can
be configured to drive the drive shaft S, e.g., to rotate the drive
shaft S, and hence drive the impeller I, e.g., rotate the impeller
I. The drive shaft S can be a solid member, which may provide
structural stability to the drive shaft S. Alternatively, the drive
shaft S can be hollow, e.g., be cannulated. The drive shaft S being
hollow can allow a guide wire to be advanced therethrough, which
may facilitate delivery of the catheter 1 into a vein, as will be
appreciated by a person skilled in the art, such as by allowing the
guide wire to be introduced into a vein and the catheter 20 to then
be advanced over the guide wire (and into a sheath (not shown) of
the system 10 advanced over the guide wire prior to the catheter 20
being advanced over the guide wire, if the system 10 includes a
sheath). For example, the guide wire can be introduced into the
jugular vein 3 (e.g., a Seldinger technique via a central venous
access under ultrasound guidance), and then the drive shaft S (and
the catheter 1 coupled thereto) can be advanced over the guide wire
into the jugular vein 3.
[0104] The pump can be configured to pump fluid at a variety of
rates. In an exemplary embodiment, the pump can be configured to
pump fluid at a rate in a range of about 100 to 1000 ml/hour, which
can provide a pressure reduction in the low pressure zone from a
pressure in a range of about 10 to 20 mmHg (the pressure in the
higher pressure zones) to a pressure in a range of about 0 to 6
mmHg (e.g., in a range of about 2 to 4 mmHg, which is a typical
normal level, or in a range of about 2 to 5 mmHg, which is also a
typical normal level). In at least some embodiments, the pump can
have a static, e.g., unchangeable, flow rate. The flow rate can
thus be predictable and/or chosen for a specific patient. In other
embodiments, the pump can have an adjustable flow rate. The flow
rate being adjustable can help the pump accommodate changes in the
patient's condition over time and/or allow the pump to be driven at
a selected rate for a particular patient. The flow rate can be
adjustable in a variety of ways, as will be appreciated by a person
skilled in the art, such as by being wirelessly adjusted using a
user-operated control device located external to the patient and
configured to wirelessly communicate with the pump (e.g., with the
controller 9) to adjust the flow rate thereof.
[0105] In at least some embodiments, the controller 9 can be
configured to be in electronic communication with at least one
pressure sensor (not shown). A person skilled in the art will
appreciate that a variety of suitable sensors can be used for
monitoring pressure, such as central venous pressure (CVP) or other
fluid pressure sensors, and blood pressure sensors. The at least
one pressure sensor can be implanted in the patient as part of the
pump, implanted in the patient as a separate component from the
pump, or the at least one pressure sensor can be located external
to the patient, such as by being on a skin surface thereof. If not
already a part of the pump so as to be in electronic communication
therewith, the at least one pressure sensor can be configured to be
in electronic communication with the pump over a communication line
such as a wired line or a wireless line. In an exemplary
embodiment, two pressure sensors can be implanted in the patient.
One of the pressure sensors can be implanted between the first and
second restrictors 2a, 2b so as to be in the low pressure zone, and
the other one of the pressure sensors can be implanted in the vein
either proximal to the proximal restrictor 2a (e.g., proximal to
the proximal inlet) or distal to the distal restrictor 2b (e.g.,
distal to the discharge opening) so as to be in one of the higher
pressure zones. The two sensors can thus allow a pressure
differential to be determined between the low pressure zone and the
higher pressure zone. In other embodiments, another number of
pressure sensors can be implanted in the patient (e.g., one, three,
four etc.) and/or the pressure sensor(s) can be implanted at other
locations.
[0106] The catheter 1 can include at least one lumen (not shown)
configured to facilitate use of the pressure sensor(s), for example
to facilitate placement of the pressure sensor(s) and/or to be
filled with a fluid such as saline to allow for external pressure
measurement.
[0107] In addition to or instead of the one or more pressure
sensors, the controller 9 can be configured to be in electronic
communication with at least one other type of sensor (not shown)
configured to sense a parameter other than pressure. Examples of
sensors that can be used to measure a parameter other than pressure
include radio frequency transmitters and receivers, fluid sensors,
bioimpedance sensors, heart rate sensors, breathing sensors,
activity sensors, and optical sensors. Examples of the measured
parameter include fluid amount (e.g., as measured by a fluid
sensor, such as a fluid sensor placed in a lung to sense fluid
amount in the lung), bioimpedance (e.g., as measured by a
bioimpedance sensor), heart rate (e.g., as measured by a heart rate
sensor), breathing rate (e.g., as measured by a breathing sensor),
patient activity level (e.g., as measured by an activity sensor),
and organ dimension (e.g., as measured by an optical sensor). The
sensor can be implanted in the patient as part of the pump,
implanted in the patient as a separate component from the pump
(e.g., implanted in an interstitial space around a lung, implanted
at a junction of a right subclavian vein of a patient and an
internal jugular vein of the patient, implanted at a junction of a
left subclavian vein of a patient and an internal jugular vein of
the patient, etc.), or the sensor can be located external to the
patient, such as by being on a skin surface thereof. If not already
a part of the pump so as to be in electronic communication
therewith, the non-pressure sensor(s) can be configured to be in
electronic communication with the pump over a communication line
such as a wired line or a wireless line. The non-pressure sensor(s)
can include one or more sensors. In embodiments including a
plurality of sensors, each of the sensors can be configured to
measure the same parameter as or a different parameter than any one
or more of the other sensors.
[0108] The motor 9 can be included as part of the pump and can be
configured to be implanted in the patient with the pump, or, as in
this illustrated embodiment, the motor 9 can be configured to be
non-implantable. The motor 9 being non-implantable can help the
pump have a smaller size and/or can allow the pump to be driven by
a more powerful motor since the motor 9 can be larger than an
implantable motor.
[0109] The controller 9 can be included as part of the pump and can
be configured to be implanted in the patient with the pump, or, as
in this illustrated embodiment, the controller 9 can be configured
to be non-implantable. The controller 9 being part of the pump can
help allow the pump to be a self-contained system, although in such
a controller requires space in the pump, which can increase a size
of the pump. The controller 9 being non-implantable can help the
pump have a smaller size and/or can allow the pump to be controlled
by a more powerful processor since the processor can be more easily
upgraded than if implanted with the pump and/or since the
processor's size can be less important when outside the pump as
opposed to inside the pump.
[0110] The controller 9 can include any type of microprocessor or
central processing unit (CPU), including programmable
general-purpose or special-purpose microprocessors and/or any one
of a variety of proprietary or commercially available single or
multi-processor systems. The controller 9 can be a component of a
control system that includes any number of additional components,
such as a memory configured to can provide temporary storage and/or
non-volatile storage; a bus system; a network interface configured
to enable the control system to communicate with other devices,
e.g., other control systems, over a network; and an input/output
(I/O) interface configured to connect the control system with other
electronic equipment such as I/O devices (e.g., a keyboard, a
mouse, a touchscreen, a monitor, etc.) configured to receive an
input from a user.
[0111] The controller 9 can be configured to receive user input
thereto to control any of a variety of aspects related to the
catheter 1, such as speed of the motor 9 and ideal range of
pressure for the low pressure zone.
[0112] In at least some embodiments, the pump can be configured to
change its pumping rate (e.g., from zero to a non-zero value, from
a non-zero value to zero, or from one non-zero value to another
non-zero value) based on pressure measured by the at least one
pressure sensor. The controller 9 can be configured to effect such
change in response to the sensed pressure. If the measured pressure
exceeds a predetermined threshold maximum pressure value, the pump
can be configured to increase its pump rate (e.g., increase from
zero or increase from some non-zero value) in an effort to decrease
the pressure. For example, if the measured pressure within the low
pressure zone is too high (e.g., is above a predetermined
threshold), the pump can increase its pump rate to decrease the
pressure within the low pressure zone. For another example, if the
measured pressure within the low pressure zone is below a
predetermined threshold, the pump can decrease its pump rate to
maintain or increase the pressure within the low pressure zone. For
yet another example, if a measured pressure differential between
the low pressure zone and the higher pressure zone is not
sufficiently great (e.g., is below a predetermined threshold), the
pump can increase its pump rate to increase the pressure
differential.
[0113] In at least some embodiments, the catheter 1 can include
only one restrictor, the proximal restrictor 2a. A higher pressure
zone can thus be proximal to the proximal restrictor, and a low
pressure zone can be distal to the proximal restrictor. The
proximal restrictor 2a positioned proximal to (e.g., upstream) of
the outflow port 4p of the thoracic duct 4 being the only
restrictor of the catheter 1, instead of the distal restrictor 2b
positioned distal to (e.g., downstream) of the outflow port 4p of
the thoracic duct 4, may help prevent back flow from the subclavian
vein 5 while providing the low pressure zone and benefit(s)
thereof.
[0114] In at least some embodiments, the catheter 1 can have a soft
atraumatic tip at its distal end 1d that is tapered in a distal
direction and that is flexible. The soft atraumatic tip may
facilitate smooth, safe introduction of the catheter 1 into the
vein 3. Exemplary materials from which the atraumatic tip can be
made include polyurethanes. The catheter may additionally include a
flexible extension similar to a guide wire tip and/or have a
hydrophilic coating, each of which may further facilitate smooth,
safe introduction of the catheter 1 into the vein 3.
[0115] In at least some embodiments, the proximal restrictor 2a can
be configured to only partially occlude the vein 3 in which the
catheter 1 is positioned when the proximal restrictor 2a in its
activated configuration. This partial occlusion may facilitate
normal fluid flow through the vein 3 even when the proximal
restrictor 2a is in the activated configuration. In embodiments in
which the proximal restrictor 2a is configured to only partially
occlude the vein 3 when in its activated configuration, the
catheter 1 can, but need not, include the proximal inlet 8p to
facilitate fluid flow through the vein 3. The partial occlusion can
be achieved in a variety of ways. For example, the proximal
restrictor 2a can have at least one lumen or hole formed
therethrough configured to allow fluid flow therethrough when the
proximal restrictor 2a is in the activated configuration. For
another example, a maximum diameter of the proximal restrictor 2a
in the activated configuration can be less than a maximum internal
diameter of the vein 3 in which the catheter 1 is positioned to
allow fluid flow around an exterior of the proximal restrictor
2a.
[0116] In at least some embodiments, the catheter 1 can include at
least one lumen or tube (not shown) configured to pass blood
therethrough outside the patient's body and back into the patient.
Such functionality may allow for the monitoring of blood volume and
performing hemofiltration.
[0117] In at least some embodiments, the catheter 1 can include one
or more radiopaque markers (not shown) configured to be visible
using an imaging technique such as fluoroscopy. The one or more
radiopaque markers can be on the catheter's shaft 7 at or near one
or more features along the shaft 7, such as any or all of the inlet
openings or any or all of the restrictors 2a, 2b. The one or more
radiopaque markers may thus facilitate proper positioning of the
shaft 7 and/or features thereon within a vein. For example, prior
to activation of the catheter's restrictor(s) 2a, 2b, the position
of the restrictor(s) 2a, 2b within the vein 3 can be verified by
visualizing the one or more radiopaque markers using an imaging
system.
[0118] The first and second restrictors 2a, 2b are discussed with
respect to FIG. 1 above as being balloons configured to inflate and
deflate, but the first and second restrictors 2a, 2b can have other
configurations. For example, the first and second restrictors 2a,
2b can each include a stent configured to expand (corresponding to
an activated configuration) and constrict (corresponding to a
relaxed configuration). The expandable/constrictable stents can
have a variety of configurations, as will be appreciated by a
person skilled in the art.
[0119] FIG. 2 illustrates another embodiment of a catheter 100 that
includes at least one restrictor (not shown in FIG. 2 for clarity
of illustration). The catheter 100 of FIG. 2 can generally be
configured and used similar to that discussed above regarding the
catheter 1 of FIG. 1, e.g., include a shaft 102, a soft,
distally-tapering atraumatic tip 104, a discharge opening 106, a
proximal inlet opening 108, an impeller 110, a drive shaft 112
extending proximally to a motor (not shown), and a distal inlet
opening 114. The motor in this illustrated embodiment is external,
similar to the embodiment discussed above regarding the catheter 1
of FIG. 1. The proximal inlet opening 108 in this illustrated
embodiment is in the form of two opposed ovular openings formed
through a sidewall of the shaft 102. The distal inlet opening 114
in this illustrated embodiment is in the form of two opposed ovular
openings formed through a sidewall of the atraumatic tip 104 distal
to the shaft 102 (one of the openings is obscured in FIG. 2). The
catheter 100 can include a bearing 116 just proximal to the
impeller 110, which may help stabilize the impeller 110 within the
shaft 102.
[0120] FIGS. 3-6 illustrate another embodiment of a catheter 200
that includes at least one restrictor (not shown in FIGS. 3-6 for
clarity of illustration). The catheter 200 of FIGS. 3-6 can
generally be configured and used similar to that discussed above
regarding the catheter 1 of FIG. 1, e.g., include a shaft 202, a
soft, distally-tapering atraumatic tip 204, a discharge opening
206, a proximal inlet opening 208, an impeller 210, a motor 212, a
drive shaft 214 extending between the impeller 210 and the motor
212, and a distal inlet opening 216. The motor 212 in this
illustrated embodiment is an on-board motor configured to be
implanted with the catheter 200. Similar to the catheter 100 of
FIG. 2, the proximal inlet opening 208 in this illustrated
embodiment is in the form of two opposed ovular openings formed
through a sidewall of the shaft 202, and the distal inlet opening
216 in this illustrated embodiment is in the form of two opposed
ovular openings formed through a sidewall of the atraumatic tip 204
distal to the shaft 202 (one of the openings is obscured in FIGS. 3
and 4).
[0121] FIGS. 7-9 illustrate another embodiment of a catheter 300
that includes at least one restrictor 318, which in this
illustrated embodiment includes only one restrictor 318 that is
located distal to an impeller 310. The catheter 300 of FIGS. 7-9
can generally be configured and used similar to that discussed
above regarding the catheter 200 of FIGS. 3-6, e.g., include a
shaft 302, a soft, distally-tapering atraumatic tip 304, a
discharge opening 306, a proximal inlet opening 308, the impeller
310, an on-board motor 312, a drive shaft 314 extending between the
impeller 310 and the motor 312, and a distal inlet opening 316. The
shaft 302 includes multiple lumens extending therethrough,
including a central lumen 320 for the impeller 310 and the motor
312 and an inflation lumen 322 for inflation/deflation of the
restrictor 318, which in this illustrated embodiment includes a
balloon. FIGS. 7-9 show the restrictor 318 in an activated
configuration, which in this illustrated embodiment is an inflated
configuration.
[0122] In at least some embodiments, a catheter including
restrictors can include a flexible membrane to which the
restrictors are appended and which enables fluid (e.g., blood flow)
to bypass a low pressure zone defined between the restrictors.
[0123] FIG. 10 illustrates one embodiment of an indwelling catheter
system 10 that can include a flexible membrane 28 and at least one
restrictor 22, 24, which are in the form of balloons in this
illustrated embodiment. As illustrated, the indwelling catheter
system 10 includes an introducer sheath 30 used to deploy a
catheter 20 having a generally elongate tubular shape, with a
circular or ovular cross-sectional geometry. The indwelling
catheter system 10 can include proximal end 10p, which can be
configured to be placed outside of a patient's body, and distal end
10d, which can be configured for placement within a patient's
vein.
[0124] The catheter 20 can have a single suction lumen 48 (see
FIGS. 14 and 15) for communicating fluid out of the vein to an
external pump, the flexible membrane 28 (which is tubular in this
illustrated embodiment), and first and second restrictors 22, 24,
which are attached to the membrane 28 and surround the membrane 28
and catheter 20. The flexible membrane 28 can be assembled to the
catheter 20 (e.g., to the shaft thereof) in any of a number of ways
to enable the flexible membrane 28 to form an ovoid or a kidney
shape upon expansion of the flexible membrane 28 (as a result of
activating the restrictors 22, 24) so that fluid can be transported
from a position within the vein proximal to the first restrictor
22, through the low pressure zone within the vein, and to discharge
the fluid at a point distal to the second restrictor 24. The
flexible membrane 28 can be attached, e.g., bonded or welded,
around a partial portion (such as a non-zero portion that is less
than 360.degree. of the catheter shaft's circumference 50) or full
portion (360.degree. around the catheter shaft's circumference 50)
of the circumference 50 of the catheter's shaft, such as in a range
of about 10.degree. to 360.degree. of the shaft's circumference 50.
FIGS. 10A and 10B illustrate the flexible membrane 28 attached to a
partial portion around the catheter shaft circumference 50. At
least one inflation port 56 is in fluid communication with an
inflation lumen (control lumen 42 discussed further below) for
inflating the first restrictor 22 and is disposed on a surface of
the flexible membrane 28 and will be underneath the first
restrictor 22 attached thereto, as discussed below. A second
inflation port (not shown) is in fluid communication with at least
one inflation lumen (control lumen 44 discussed further below) for
inflating the second restrictor 24 and is disposed on a surface of
the flexible membrane 28 and will be underneath the second
restrictor 22 attached thereto, as discussed below. As shown in
FIG. 10B, which has a portion of the flexible membrane 28 removed
for clarity of illustration, at least one suction port 26 is
extending through an external surface of the catheter 20 such that
it is in fluid communication with a suction lumen 48.
[0125] Following attachment of the flexible membrane 28 to the
catheter 20, the restrictors 22, 24 can be attached to the catheter
20. As shown in FIG. 10C, the first restrictor 22 can be bonded or
welded to an outer surface of the flexible membrane 28 over the
inflation port 56 so that the first restrictor 22 surrounds the
outer circumference 52, 54, of the catheter 20 and the flexible
membrane 28. As shown in FIG. 10D, edges of the first restrictor 22
can be flattened to extend beyond the collapsed balloon and bonded
to the flexible membrane 28. The second restrictor 24 can be
attached to the catheter 20 similar to the first restrictor's
attachment to the catheter 20. In an alternate embodiment, as shown
in FIG. 10E, a restrictor 22' has at least one edge 52' thereof
folded under and bonded beneath the collapsible tube of the
restrictor 22'. One or both of the first and second restrictors 22,
24 can be attached to the catheter 20 similar to the attachment of
the restrictor 22' of FIG. 10E.
[0126] FIGS. 10E-10H illustrate one embodiment of a method for
manufacturing a torus-shaped restriction member 502 configured to
be attached to a catheter shaft as discussed herein. As shown in
FIG. 10F, a pattern 500 is formed by a process such as blow molding
or dip molding. For example, a slope of the mold pattern can be
formed in a continuous shape without sharp corners or directional
reversion. As shown in FIG. 10G, after the restriction member 502
is formed using the pattern 500, it is assembled onto a collapsible
sleeve 510. During the assembly, two legs 504, 506 of the
restriction member 502 are pushed towards each other and bonded
together. The restriction member 502 maintains an opening 508
between the legs 504, 506 to enable the formation or positioning of
an inflation port in the catheter that will be used to inflate the
restriction member 502. As shown in FIG. 10H, after the legs 504,
506 are brought together, as explained above, a lower section of
the restriction member 502 is inverted inward. The curvature of the
restriction member 502 is maintained in the opposite direction
thereby maintaining material continuity to form the restriction
member 502, as illustrated.
[0127] The suction lumen 48 can accommodate the flow of fluid from
the vein in which the catheter 20 is implanted to a pump external
to the patient, when deployed, and the membrane 28 can enable fluid
returned from the pump to bypass the portion of the vein occluded
by the restrictors 22, 24. As shown in FIGS. 11A, 11B, 14, and 15,
the suction lumen 48 can communicate with the suction port 26,
formed in an outer wall of catheter 20, and can extend to a
proximal end of the catheter 20. The proximal end of the catheter
20 can include a hub 34 which communicates with discharge tubing
(not shown) coupled to the pump external to the patient (not shown)
to communicate fluid withdrawn from within the low pressure zone
between the restrictors 22, 24 through the suction lumen 48 of the
catheter 20. Fluid present in the vein in which the catheter 20 is
implanted, and between the deployed restrictors 22, 24 of the
catheter 20, is drawn from the vein into the suction port 26 and
into the suction lumen 48 of catheter 20 so that it can be
communicated to the external pump (not shown) via the suction lumen
48 and the discharge tubing.
[0128] The tubing extending out of the pump (not shown) to return
fluid to the catheter system 10 can be coupled to the sheath 30 at
a discharge port 36 (see FIGS. 10, 12A, 12B, and 13). Fluid
returned from the pump will enter the discharge port 36 and be
discharged within the vein external to the catheter 20. The pump
can facilitate fluid movement from the catheter 20 through the
suction lumen 48 and into the discharge tubing through which it is
communicated to the pump. The discharge port 36 can be configured
to connect to an end of the drainage tubing having its other end in
fluid communication with the pump. The discharge port 36 can, as
shown, include surface features formed thereon and extending
therearound to facilitate its connection to the discharge
tubing.
[0129] As shown in FIGS. 10, 10A, 11A, and 11B, the first
restrictor 22 can be downstream of (e.g., distal to) a proximal
opening 28p of the membrane 28, and a distal opening 28d of the
membrane 28 can be downstream of second restrictor 24. Thus, when
the first and second restrictors 22, 24 are activated or deployed
to fully occlude the vein, the lumen of the membrane 28 can provide
a bypass route for fluid (e.g., blood) returning from the external
pump or otherwise flowing downstream within the vein external to
catheter 20. In other words, even though the vein is occluded by
the restrictors 22, 24, blood and other fluid can flow through the
lumen of the membrane 28 to flow from a position upstream of (e.g.,
proximal to) the proximal restrictor 22 to a position downstream of
the distal restrictor 24. Although the catheter 20 and the flexible
membrane 28 are illustrated to be oriented in a side-by-side
relationship with respect to one another, they can be oriented in
any other suitable manner, including having one member disposed
within the other member. Also, the catheter 20 can have any number
of additional lumens, which can function, for example, as control
lumens to facilitate activation of the restrictors 22, 24 and/or to
sense pressure at various locations within the vein in which the
catheter 20 is disposed.
[0130] The catheter 20 can include a distal atraumatic tip 12 that
can facilitate placement of the catheter 20 into the vein of a
patient. The distal atraumatic tip 12 can have an aperture such
that the tip 12 has a lumen extending therethrough. The lumen of
the tip 12 can be configured to allow passage of a guide wire
through the tip 12. The catheter 20, including the flexible
membrane 28 and the restrictors 22, 24, can be advanced over the
guide wire to be deployed from the sheath 30. The lumen and the
aperture can be sized to accommodate a standard guide wire of size
such as about 0.014'', about 0.018'', about 0.035'', or about
0.038''. In addition to or instead of the catheter 20 including the
distal atraumatic tip 12, the sheath 30 can include a distal
atraumatic tip to facilitate advancement of the sheath 30 having
the catheter 20 disposed therein to a location where the catheter
20 is to be released from (e.g., advanced distally out of) the
sheath 30. The sheath's distal atraumatic tip can include a lumen
to allow passage of a guide wire through the tip, as discussed
above.
[0131] As shown in FIG. 11B, the catheter 20 can include one or
more radiopaque markers 21 configured to be visible using an
imaging technique such as fluoroscopy. As also shown in FIG. 11B,
the catheter 20 can include one or more sensors 23, which in this
illustrated embodiment includes an optic pressure transducer,
located between the restrictors 22, 24 and hence within a low
pressure zone created therebetween. The pressure transducer 23 is
configured to continually monitor pressure within the low-pressure
zone so pump function can be adjusted if necessary to keep the
pressure at a desired level (in a desired range of about 2 to 5
mmHg, etc.) and at the location of the discharge lumen so internal
jugular vein pressure can be monitored. The pressure transducer 23
is also configured to provide CVP measurements when the restrictors
22, 24 are deflated.
[0132] As shown in FIG. 12B, the catheter system 10 can include an
eyelet 25 configured to facilitate securement of the system 10 to a
patient during use. For example, the eyelet 25 can be secured by a
suture to the patient's skin. The catheter shaft can be locked in
position relative to the sheath 30 using, for example, a Tuohy
Borst valve, such that the catheter 20 can be secured to the
patient during use via the sheath 30. The eyelet 25 may thus be
secured to the patient after the catheter 20 has been advanced
through the sheath 30 to be in a desired position within the
patient to help ensure that the system 10 is secured to the patient
with the catheter 20 in its desired position.
[0133] As shown in FIGS. 10, 12, and 13, the sheath 30 can include
a plurality of ports 32a, 32b, 32c in fluid communication with
respective ones of a plurality of control lumens 42, 44, 46 within
the catheter 20. As shown in FIGS. 14-16, the first and second
ports 32a, 32b respectively communicate with the first and second
control lumens 42, 44, which can be configured to deliver fluid to
the first and the second restrictors 22, 24, respectively, to
control the activation and deactivation of the restrictors 22, 24.
The third port 32c can communicate with the third control lumen 46,
which can communicate with an opening in the catheter 20 for
purposes of sensing a pressure within the vein, as discussed above.
The third control lumen 36 includes one or more pressure sensors in
this illustrated embodiment, but any one or more of the control
lumens 42, 44, 46 can include one or more pressure sensors, to be
used for sensing pressure at various locations along the vein in
which the catheter 20 is implanted, such as between the proximal
and distal restrictors 22, 24 and upstream of the proximal
restrictor 22.
[0134] As shown in FIGS. 14 and 15, the suction lumen 48 is
internal to the catheter 20 and the flexible membrane 28 that is
external to the catheter 20 and is oriented in a side-by-side
arrangement with respect to the catheter 20. The control lumens 42,
44, 46 can be disposed within the catheter 20, such as within the
wall of the catheter 20, as shown. As indicated above, the
cross-sectional arrangement of catheter 20 can take various forms,
and the relative positioning of the suction lumen 48 and the
control lumens 42, 44, 46 can vary. More or fewer suction lumens 48
and control lumens 42, 44, 46 can be provided in the catheter 20.
For example, one or more additional control lumens can accommodate
a variety of non-pressure sensors, as discussed above.
[0135] Sizes of the catheter 20, the sheath 30, and the flexible
membrane 28 can vary depending upon the catheter system's intended
uses. Generally, the catheter 20 can have a length in the range of
about 25 to 40 cm. In addition, the diameter can also vary, but
suitable catheters will typically be in the range of about 8 to 18
Fr. Other catheters described herein can have a similar size, e.g.,
a length in the range of about 25 to 40 cm and a diameter in the
range of about 8 to 18 Fr. The sheath 30 can have a length in the
range of about 10 to 25 cm, can have an internal diameter in the
range of about 2.5 to 5.5 mm, and can have an external diameter in
the range of about 3 to 6 mm. In one embodiment, the catheter 20
can have a diameter of about 8 Fr and the sheath 30 can have a
diameter of about 11 Fr. The flexible membrane 28 can have a length
in the range of about 50 to 150 mm. A distance between the distal
end of the sheath 30 and the proximal end of the flexible membrane
28 can be up to about 100 mm. The diameter of the control lumens
42, 44, 46 can vary depending upon the requirements of a given
application. The suction lumen 48 can have a diameter in the range
of about 1 to 4 mm, while pressure inflation lumens can have a
diameter in the range of about 0.1 to 1 mm.
[0136] FIGS. 17A-17C illustrate one example of the catheter 20
implanted within a patient, in particular within a jugular vein 80
of the patient. FIG. 17B also illustrates a location of the low
pressure zone and illustrates fluid flow through the catheter 20 as
indicated by two sets of arrows into and one set of arrows out of
the catheter 20. FIG. 17C also illustrates one embodiment of a pump
27, a peristaltic pump (such as a peristaltic blood pump motor
model DriveSure.TM. 48 VDC, Head model 520RL2, available from
Watson Marlow), configured to pump fluid in and out of the catheter
system 10 via the ports 32a, 34. As shown, the first restrictor 22,
which in this illustrated embodiment is positioned at a region of
the catheter 20 that is proximal to the suction port 26 and that
marks the proximal or upstream boundary of the low pressure zone,
can be positioned proximal to (upstream of) a point at which the
patient's subclavian vein 82 enters the jugular vein 80. The second
restrictor 24, which in this illustrated embodiment is positioned
distally of the first restrictor 22 and between the suction port 26
and the distal end of the catheter 20, can be positioned distal to
(downstream of) the point at which the subclavian vein 82 enters
the jugular vein 80, and the second restrictor 24 can be in the
patient's innominate vein 84. Alternatively, the catheter 20 can
treat both lymphatic ducts by placing the first restrictor 22
proximal to (upstream of) the point at which the subclavian vein 82
enters the jugular vein 80 and placing the second restrictor 24
distal (downstream of) to the point at which both of the patient's
innominate veins enters the subclavian vein 82. Alternatively, the
second restrictor 24 can be positioned in the subclavian vein
82.
[0137] The catheter 20 can be positioned with the jugular vein 80
as shown in FIGS. 17A and 17B in any of a variety of ways. For
example, the positioning can be conducted using a 12 Fr sheath 30
to puncture the venous wall. The sheath 30 can be advanced into the
vein 80 with the catheter 20, the flexible membrane 28, and the
restrictors 22, 24 collapsed and contained therein. After insertion
of the sheath 30, the catheter 20 along with the flexible membrane
28 and the restrictors 22, 24, can be advanced through the distal
tip of the sheath 30 and positioned downstream of the sheath 30.
Alternatively, the sheath 30 can be introduced first, and then the
catheter 20 can be introduced by being advanced through the sheath
30. Regardless of whether the sheath 30 and the catheter 20 are
introduced sequentially or simultaneously, the catheter 20 can be
configured to be removed from the sheath 30 at any time. If at any
time throughout a procedure there might be a question with regards
to the integrity of the catheter 20, the catheter 20 being
removable with the sheath 30 remaining in place within the patient
allows the catheter 20 to be replaced with a new one introduced
into the sheath 30 or for the catheter 20 to be reintroduced into
the sheath 30 if the catheter's integrity is deemed acceptable.
[0138] The distal restrictor 24, when activated, isolates the
incoming blood flow from the subclavian and jugular veins 82, 80
from the blood flow of the innominate vein 84 and ensures that all
incoming blood is directed to the pump 27. The proximal restrictor
22, when activated, isolates the blood flow from the jugular vein
80 and ensures that all blood flow from a position upstream of the
proximal restrictor 22 is transported through the flexible membrane
28. The pump is activated to maintain the jugular and innominate
vein pressure and thus the nominal blood flow. The proximal
restrictor 22, when activated, directs the blood flow from the
jugular vein 80 and from the discharge port 36 within the sheath 30
down to the innominate vein 84. Actuation of the pump helps to
create a low pressure zone in the vicinity of the junction of the
jugular vein 80 and the subclavian vein 82 by withdrawing fluid in
this region, recirculating it through the pump, and discharging the
fluid upstream of this region through the sheath 30. Because the
outflow of the thoracic and lymphatic ducts is located in this
region, the lower pressure will facilitate drainage of lymphatic
fluid.
[0139] The catheter 20 can be implanted in the jugular vein 80 as
shown in FIGS. 17A and 17B in any of a variety of ways. FIGS. 18-20
illustrate one embodiment of implanting the catheter 20 can be
implanted in the jugular vein 80. The catheter 20 can be similarly
implanted in another vein, and other catheters described herein can
be implanted in a vein similar to that discussed with respect to
FIGS. 18-20.
[0140] FIGS. 18 and 19 illustrate the indwelling catheter system 10
(only a distal portion thereof is shown in FIG. 18) in an initial
configuration in which the catheter 20 is disposed within the
sheath 30 in a compressed configuration. In the initial
configuration, the sheath 30 can have the catheter shaft 20
positioned therein, encircled by a compressed flexible membrane 28
further surrounded by compressed restriction members 22, 24.
[0141] A distal portion of the indwelling catheter system 10, e.g.,
a distal portion of the sheath 30, in the initial configuration can
be inserted into the jugular vein 80 of the patient, which is the
right internal jugular vein in this illustrated embodiment. A
proximal portion of the indwelling catheter system 10, e.g., a
portion including the ports 32, 34, 36, can remain outside the body
of the patient to facilitate access to the ports 32, 34, 36. With
the distal portion of the catheter system 10 at the target site
(e.g., within the vein in which the catheter 20 is to be
implanted), the catheter 20 can be advanced out of the sheath 30,
as shown in FIG. 20, such that a proximal portion thereof is
positioned within the jugular vein 80 and a distal portion thereof
is positioned within the SVC 84. The suction port 26 disposed
between the first and second restriction members 22, 24 enables
suction of blood deposited within the low pressure zone from the
subclavian vein 82 and from the innominate vein 84. Such
arrangement enables drainage of both the patient's right lymphatic
duct and thoracic duct. After positioning of the catheter 20 within
the patient, the first and second restrictors 22, 24 can be
expanded, e.g., moved from their relaxed configuration to their
activated configuration, as shown in FIGS. 17A and 17B. The
expansion of the restrictors 22, 24 also expands the flexible
membrane 28, e.g., moved the flexible membrane 28 from a relaxed
configuration to an activated configuration. As mentioned above,
the restrictors 22, 24 can be expanded simultaneously or
sequentially. As mentioned above, the expansion of the restrictors
22, 24 isolates a portion of the vein 80 in which the catheter 20
is deployed from a surrounding area, and, thus, an area (e.g., a
low pressure zone) proximate to the thoracic duct is isolated and
fluid can be removed via the suction port 26 positioned on the
catheter 20 located within the isolated area.
[0142] The catheter system 10 discussed above is configured to pump
blood out of a patient's body and back into the body. A catheter
system can instead include an impeller, such as in the catheter
embodiments of FIGS. 1-6, such that blood need not be pumped out of
and back into a patient's body and features of the catheter system
10 related thereto need not be included (e.g., a pump, a discharge
port, and related tubing need not be included). The catheter system
including an impeller can otherwise be similar to the catheter
system 10, e.g., include a flexible membrane, include a sheath,
etc.
[0143] The catheters described herein can be used in a variety of
surgical methods, including surgical methods for treating pulmonary
edema. The method can include verifying a location of the patient's
thoracic duct and/or the patient's lymphatic duct, which can help a
surgeon and/or other medical professional involved in performing a
surgical procedure that includes implanting the catheter verify
that the restrictor(s) of the catheter are implanted in the correct
location within the patient. The verification can be performed in
any of a variety of ways, as will be appreciated by a person
skilled in the art, such as by using an imaging technique such as
echo or fluoroscopy. In an exemplary embodiment, the verification
can include advancing a set of pig tailed wires into the patient's
subclavian or jugular veins and advanced toward a junction of the
jugular and subclavian veins. Once one of the pig tailed wires
enters the lymphatic duct or the thoracic duct, that one of the pig
tailed wires can open itself inside the duct it entered, e.g., due
to a default expanded configuration of the wire. The pig tailed
wires can include, for example, a default expanded circle size of 4
cm. The location of the entered duct can be verified using an
imaging technique that visualizes the expanded wire therein.
[0144] The verification can occur after the implantation of the
catheter such that the implanted location of the catheter can be
determined in view of the verification and adjusted if need be in
view of the verification. Additionally or alternatively, the
verification can be performed prior to the implantation of the
catheter. Similarly, the verification can be performed prior to
and/or after the restrictor(s) are moved from the relaxed
configuration to the activated configuration to verify the
position(s) of the restrictor(s), and the verification can be
performed prior to and/or after one or more sensors are implanted
in the to verify that the sensor(s) are desirably positioned. As
discussed above, the sensor(s) in some embodiments are not
implanted and are instead located outside the patient's body,
and/or at least one sensor is implanted and at least one sensor is
located outside the patient's body. Various embodiments of
positioning tubes such as catheters is further described in U.S.
Patent Publication No. 2015/0343136 entitled "System And Method For
Treating Pulmonary Edema" filed Feb. 19, 2015, which is hereby
incorporated by reference in its entirety.
[0145] With the catheter implanted, the restrictor(s) in the
activated configuration, and, if being used in the system, the
sensor(s) positioned, fluid flow can be controlled with the pump.
The control can generally occur as described above. In at least
some embodiments, controlling the pump can include continuously
running the pump. In at least some embodiments, controlling the
pump can include periodically running the pump. In periodically
running the pump, the pump can default to an idle state in which
the pump is not pumping fluid. For example, in response to receipt
of a user input requesting pumping, e.g., input by a user to an I/O
device in electronic communication with the pump via a controller,
input wirelessly to the pump, etc., the pump can be actuated so as
to run and pump fluid. The pump can continue pumping until
occurrence of a stop condition. Examples of the stop condition
include a predetermined amount of time passing after the pump
starts running and a second user input being received that requests
pumping to stop. In response to the stop condition occurring, the
pump can be actuated to return to its idle state. For another
example, in response to sensing a particular parameter value (e.g.,
a particular pressure value, etc.) with one or more sensors, the
pump can be actuated so as to run and pump fluid or the pump can be
stopped so as to stop pumping fluid. The parameter can continue
being measured with the one or more sensors, thereby allowing the
pump to be controlled in real time in response to measured
values.
[0146] In at least some embodiments, a control module can be
configured to control the operation of a system including a
catheter. For example, for a system configured to treat pulmonary
edema, the system can include a control module to receive
information from sensor(s) of the system, to activate restrictor(s)
of the system, and adjust a flow rate of a pump of the system. Upon
receiving information from the sensor(s), the control module can be
configured to actuate the pump function. The control module can
further be configured to process information received from the
sensor(s) to alter restriction volume, such as an inflation amount
of each of the system's one or more restrictors. In at least some
embodiments, the system can include a plurality of sensors and the
control module can be configured to receive information from at
least one of the sensors regarding pressure within a jugular vein
of a patient, information from at least one of the sensors
regarding pressure at the bifurcation of the patient's jugular and
subclavian veins, and information from at least one of the sensors
regarding pressure at the patient's innominate vein. Embodiments of
a control module include the motor/controller 9 of FIG. 1, a
control module 600 of FIG. 21, a control module of FIG. 22, and a
control module 826 of FIGS. 26.
[0147] The control module 600 of FIG. 21 includes a computer (e.g.,
a PC, etc.) 602, a controller 604 in the form of an embedded real
time controller, a safety relays board 606, a pump 608 in the form
of a peristaltic pump, pump pressure sensors 610 that include a
pump inlet pressure sensor and a pump outlet pressure sensor,
catheter pressure sensors 612 that include a first catheter
pressure sensor configured to be positioned in a jugular vein of a
patient and a second catheter pressure sensor configured to be
positioned in a subclavian vein of the patient, an air bubble
detector 614, an alarm notification mechanism 616 in the form of an
alarm buzzer, a fan 618 configured to provide cooling for safety,
an electrical inlet 620, and a power supply 622 in the form of an
AC to DC power supply. The control module 600 can also include a
drip chamber (not shown) configured to allow gas (e.g., air) to
rise out of blood flowing through the control module 600 before the
blood returns to the patient to facilitate patient safety. The
computer 602 is shown as part of the control module 600 in this
illustrated embodiment, but the computer 602 can be a separate
component from the control module 600 and instead be coupled
thereto electronically (wired or wireless).
[0148] The computer 602 is configured to act as a control panel for
a user to monitor patient and pump parameters so the user can make
decisions regarding patient care. The computer 602 includes a user
interface on a display thereof to facilitate providing of the
parameters to the user. The computer 602 is configured to provide
on the user interface identified safety-related concerns, such as
air bubbles detected by the air bubble detector 614, and/or to
cause the notification mechanism 616 to provide notification of the
identified safety-related concerns to the user, such as by buzzing
the alarm buzzer, by illuminating a light coupled to the control
module 600, by sending an electronic message such as an email or a
text message to the user, by showing a message on the computer's
display, etc.
[0149] The computer 602 is configured to receive real time
information from various components of the control module 600, via
the real time controller 604, which may facilitate control of the
catheter system that includes the control module 600, facilitate
providing notice to a user of system functionality, and/or
facilitate collection of data for later analysis for patient
treatment purposes. The user notification allows the user to take
one or more corrective actions to address the subject matter of the
notification, such as adjusting a speed of the pump 608, deflating
restrictor(s) of the catheter system to allow catheter removal,
powering off the control module 600, etc. For example, the computer
602 receives real time pump outlet pressure information from the
pump outlet pressure sensor 610 to allow the computer 602 to
determine whether the pump outlet pressure is within a
pre-programmed acceptable safe range and, if not, to adjust a speed
of the pump 608 to urge the pump outlet pressure to be within the
safe range and/or cause a user notification to be provided
indicating a possible unsafe pressure situation. For another
example, the computer 602 receives real time pump inlet pressure
information from the pump inlet pressure sensor 610 to determine
whether the pump inlet pressure is within a pre-programmed
acceptable safe range and, if not, to adjust a speed of the pump
608 to urge the pump inlet pressure to be within the safe range
and/or cause a user notification to be provided indicating a
possible unsafe pressure situation. For yet another example, the
computer 602 receives real time jugular vein pressure information
from the first catheter pressure sensor 612 to determine whether it
is within a pre-programmed acceptable safe range and, if not, to
adjust a speed of the pump 608 to urge the jugular vein pressure to
be within the safe range and/or cause a user notification to be
provided indicating a possible unsafe pressure situation. For still
another example, the computer receives subclavian vein pressure
information from the second catheter pressure sensor 612 to
determine whether it is within a pre-programmed acceptable safe
range and, if not, to adjust a speed of the pump 608 to urge the
subclavian vein pressure to be within the safe range and/or cause a
user notification to be provided indicating a possible unsafe
pressure situation. For another example, the computer 602 receives
air bubble information from the air bubble detector 614 to
determine if blood being pumped by the pump 608 includes an amount
of air bubbles over a predetermined threshold level and, if so,
adjust a speed of the pump 608 to reduce the level of air bubbles
and/or cause a user notification to be provided indicating a
possible thrombosis risk due to air bubble presence. For yet
another example, the computer 602 receives pump rotation
information from a pump tachometer coupled to the pump 608 to
determine whether the pump 608 is operating within its preset
operational limit and, if not, to adjust a speed of the pump 608 to
be within its preset operational limit and/or cause a user
notification to be provided indicating a possible pump failure
situation. For another example, the computer 602 receives fan
rotation information from a fan tachometer coupled to the fan 618
to determine whether the fan is rotating above a predetermined
threshold and, if so, to adjust a speed of the fan 618 to be within
its preset operational limit and/or cause a user notification to be
provided indicating a possible overheating situation.
[0150] In an exemplary embodiment, the computer 602 is configured
to provide the user notification without causing any automatic
corrective action to be performed in order to increase user
control. In other embodiments, the computer 602 is configured to
automatically cause a corrective action to be performed for certain
conclusions drawn from received information, namely conclusions
that pose an imminent risk to patient safety and/or control module
failure, such as automatically reducing a speed of the pump 608 if
it is determined to be running above its maximum safe limit or
stopping the pump 608 if too many air bubbles are detected, and to
not automatically cause a corrective action to be performed for all
other conclusions drawn from received information.
[0151] FIG. 22 illustrates one embodiment of the control module 600
of FIG. 21. The control module includes a housing 700 having
electronic components disposed therein (e.g., the controller 604,
the safety relays board 606, the alarm notification mechanism 616,
the fan 618, the power supply 622, etc.). Attached to the housing
700 are a pump 702, pump pressure sensors that include a pump inlet
pressure sensor 704 and a pump outlet pressure sensor 706, a drip
chamber 708, an air bubble detector 710, a catheter pressure sensor
inlet 712 configured to couple to the catheter pressure sensors, an
inlet blood line clamp 714 configured to clamp to an inlet tube of
a blood line through which blood flows from the patient to the pump
702, and an outlet blood line clamp 716 configured to couple to an
outlet tube of the blood line through which blood flows from the
pump 702 to the patient. The blood line can include any of a
variety of tubing sets, as will be appreciated by a person skilled
in the art. The control module of FIG. 22 does not include a
computer and is configured to electronically couple to a
computer.
[0152] A control module configured to control the operation of a
system including a catheter can include one or more feedback loops
to adjust performance of the system to create and maintain a low
pressure zone while lymphatic fluid is cleared in a context of a
system configured to treat pulmonary edema in a patient. FIGS.
23-28 illustrate one embodiment of a process to create a low
pressure zone and transport fluid from a low pressure zone back
into the venous system of a patient in a context of a system
configured to treat pulmonary edema in a patient.
[0153] As shown in FIG. 23, a distal portion of a catheter system
800 is introduced into a patient. A distal end of a sheath 802 is
positioned within a jugular vein 804 of the patient proximal to a
subclavian vein 806 of the patient and thoracic duct 808 outlet. A
distal end of a catheter 814, e.g., an atraumatic distal tip 816
thereof, just beyond the distal end of the sheath 802 is also
positioned within the jugular vein 804 proximal to the subclavian
vein 806 and the thoracic duct 808 outlet. A guidewire 810
extending through the sheath 802 and the catheter 814 extends
distally beyond the sheath's distal end and the catheter's distal
end and extends distally past the subclavian and jugular
bifurcation to be in an innominate vein 812 of the patient. Blood
continues to flow normally from the jugular vein 804 into the
innominate vein 812 and from the subclavian vein 806 into the
innominate vein 812, with the blood flowing around the sheath 802
and catheter 814. A pressure at the subclavian and jugular
bifurcation at this point is shown in FIG. 23 as being at 15
mmHg.
[0154] As shown in FIG. 24, the catheter 814 is then advanced
distally from the sheath 802 over the guidewire 810 to extend
across the subclavian and jugular bifurcation. A proximal
restrictor 818 of the catheter 814 is positioned proximal to
(upstream of) the subclavian and jugular bifurcation, and hence
proximal to the thoracic duct 808 outlet, and a distal restrictor
820 of the catheter 814 is positioned distal to (downstream) of the
subclavian and jugular bifurcation, and hence distal to the
thoracic duct 808 outlet. The proximal and distal restrictors 818,
820 are collapsed. A flexible membrane 822 of the catheter 814 is
also collapsed. Blood continues to flow normally from the jugular
vein 804 into the innominate vein 812 and from the subclavian vein
806 into the innominate vein 812, with the blood flowing around the
sheath 802 and catheter 814.
[0155] As shown in FIG. 25, the restrictors 818, 820 and the
flexible membrane 822 are then expanded. Blood now flows from the
jugular vein 804 into the flexible membrane 822 and flows
therethrough across the subclavian and jugular bifurcation into the
innominate vein 812. Blood is now not flowing from the subclavian
vein 806 into the innominate vein 812.
[0156] As shown in FIG. 26, a pump 824 of a control module 826 is
activated (e.g., is turned on, as indicated by an illuminated power
light shown standing alone in FIG. 26 to allow it to be visible in
FIG. 26) to suction blood into proximal and distal suction ports
828, 830 of the catheter 814 that are located between the
restrictors 818, 820. The suctioning draws the blood into the
catheter 814 (e.g., into the catheter shaft's inner lumen) and
toward the pump 824, and the suctioning reduces the pressure at the
subclavian and jugular bifurcation. A pressure at the subclavian
and jugular bifurcation at this point is shown in FIG. 26 as being
at 4 mmHg, which is reduced from the previous 15 mmHg value at the
subclavian and jugular bifurcation. The pressure is measured at the
subclavian and jugular with a first pressure sensor 832 of the
catheter 814. The pressure proximal to the proximal restrictor 818
is shown as 15 mmHg in FIG. 23. The pressure proximal to the
proximal restrictor 818 is measured with a second pressure sensor
834 of the catheter 814 (see FIG. 26A). A low pressure zone has
thus been formed between the restrictors 818, 820. Blood now flows
from the jugular vein 804 into the flexible membrane 822 and flows
therethrough across the subclavian and jugular bifurcation into the
innominate vein 812. Blood now flows from the subclavian vein 806
into the catheter 814.
[0157] As shown in FIG. 27, blood returns to the sheath 802 from
the pump 824 to flow into the flexible membrane 822 proximal to the
proximal restrictor 818 and across the subclavian and jugular
bifurcation into the innominate vein 812. Blood now flows from the
jugular vein 804 into the flexible membrane 822 and flows
therethrough across the subclavian and jugular bifurcation into the
innominate vein 812. Blood now flows from the subclavian vein 806
into the catheter 814 and returns to the patient via the sheath
802. FIG. 28 shows the low pressure zone with a pressure of 4 mmHg
and pressures on either side thereof as being at 15 mmHg.
[0158] The blood flow of FIGS. 27 and 28 remains until the pump 824
is deactivated (e.g., turned off) and/or the restrictors 818, 820
are collapsed. The control module 826 functions as discussed
herein, allowing data for various parameters to be collected and
analyzed.
[0159] FIG. 29 illustrates another embodiment of a process 400 to
create a low pressure zone and transport fluid from a low pressure
zone back into the venous system of a patient in a context of a
system configured to treat pulmonary edema in a patient. At step
402 of the process 400 a control module acquires baseline
pressure(s), such as a jugular pressure and a baseline bifurcation
pressure. The baseline bifurcation pressure is acquired, for
example, by the pressure sensors of a catheter of the system when
the one or more pressure sensors are out of the system's sheath.
Once the catheter is taken out of the sheath, the pressure sensors
can read baseline pressure within the patient. After the baseline
pressure is read, the catheter can be advanced to its final
position within the patient.
[0160] The control module at step 404 of the process 400 measures a
diameter of the patient's jugular vein and a diameter of the
patient's innominate vein. The diameters can be measured, for
example, by a correlation between a volume that is inflated into
the catheter's restriction members and the pressure reading at the
catheter's pressure sensors. When the distal one of the restriction
members (e.g., the restriction member positioned in the patient's
innominate vein) is inflated to the level of the vein in which it
is positioned suddenly there is an abrupt increase pressure, which
is read by the catheter's pressure sensors (e.g., one pressure
sensor in the patient's jugular vein and another pressure sensor in
the patient's innominate vein). This abrupt increase indicates that
the vessel diameter has been achieved. From the amount of volume
that was inflated, the diameters are now known since there exists a
1:1 correlation between the volume and diameter curve for the
restriction members.
[0161] At step 406 of the process 400 the control module selects an
inflation size of the system's restrictor(s) and can calculate a
volume of the restrictor(s). In the distal one of the restriction
members, the inflation size is measured as described above, for
example. In the proximal one of the restriction members (e.g., the
restriction member positioned in the patient's jugular vein), the
inflation size is determined, for example, using a visualization
technique such as ultrasound to measure the correct diameter, as it
can be easily visualized. At step 408 of the process 400, a target
bifurcation pressure is calculated by the control module. The
target pressure is taken to be, for example, over 50% reduction
from the baseline pressure.
[0162] At step 410 of the process 400, a catheter of the system is
placed within the patient, for example by being distally advanced
out of a sheath as discussed above. At step 412 of the process 400,
a flow rate of a pump of the system equals zero, and a volume of
each of the system's one or more restrictors equals zero. Next, at
step 414 of the process 400, the control module causes the
restriction member(s) to be deployed (e.g., inflated) to
accommodate the vein size. The restriction member(s) are inflated
to the inflation size selected above.
[0163] At step 416 of the process 400, the control module
determines if the baseline bifurcation pressure (Pb) is greater
than the target bifurcation pressure (Pbt). If the baseline
bifurcation pressure is greater than the target bifurcation
pressure, the control increases the pump flow at step 418 of the
process 400. The process 400 then reverts back to repeat step 416
to re-measure the target bifurcation pressure. With two pressure
sensors (in the innominate and jugular veins in this example) that
work simultaneously, this process 400 is accurate and real time. If
the baseline bifurcation pressure is not greater than the target
bifurcation pressure, then the process 400 proceeds to step 420 in
which the control module determines if the baseline bifurcation
pressure is less than the target bifurcation pressure minus a
safety delta (SD). The safety delta comes from different scenarios.
The target bifurcation pressure is typically in a range of 0 to 5
mmHg. However, if the baseline pressure is very high (e.g., above
about 15 mmHg) it can also be considered a successful treatment if
the target pressure is above the typical range, e.g., is in a range
of about 5 to 7 mmHg. Therefore, for each baseline pressure there
is a target pressure which can be more than 50% of the baseline
pressure. If the baseline bifurcation pressure is less than the
target bifurcation pressure minus the safety delta, the process 400
proceeds to step 422 to reduce the initial pump flow, and the
process 400 re-measures the target bifurcation pressure at step
416. If the baseline bifurcation pressure is not less than the
target bifurcation pressure minus the safety delta, the process 400
advances to step 424 and a working system condition is
achieved.
[0164] One skilled in the art will appreciate further features and
advantages of the invention based on the above-described
embodiments. Accordingly, the invention is not to be limited by
what has been particularly shown and described, except as indicated
by the appended claims. All publications and references cited
herein are expressly incorporated herein by reference in their
entirety.
* * * * *